Furnace and method for heating fluids



Jan. 5, 1937. J. G. ALTHER FURNACE AND METHOD FOR HEATING FLUIDSOriginal Filed Dec. '7, 1932 INVENTOR JOSEPH G. ALTHER Patented Jan. 5,1937 UNITED STATES 2,066,664 FURNACE AND METHODFOR HEATING FLUIDS JosephG. Alther, Chicago, 111., assigno'r to Universal Oil Products Company,Chicago, Ill., a corporation of Delaware Application December '1, 1932,Serial No. 646,072 Renewed May 23, 1936 7 Claims.

This invention particularly refers to an improved form of fumace,particularly adapted to the heating of hydrocarbon oils to the hightemperatures required for their pyrolytic conversion,

of the type wherein opposite sides of the tubes, comprising the fluidconduit through which the oil is passed, are subjected to substantiallyequal rates of heating.

More specifically the invention embodies the improved method ofoperating improvement to this type of furnace which comprises supplyingradiant heat to opposite sides of the tubes of the fluid conduit fromflames and heated refractory surfaces and simultaneously supplyingconvection heat to opposite sides of the tubes by passing thereover astream of hot combustion gases in a direction countercurrent to thedirection of the flame.

The method of heating provided by the present invention permits a moreuniform distribution of heat to various portions of the fluid conduit,the

maximum radiant heat input to the tubes occurring in that portion oftheheatin'g coil or fluid conduit wherein the convection heat input 25is at a minimum, the input of radiant heat gradu-' ally decreasing asthe convection heat input increases. Thus, the radiant and convectioncomponents of the total heat imparted to the tubes have acounter-balancing effect, the increasing 30 intensity of one tending tocounteract the decreasing intensity of the other.

The accompanying diagrammatic drawing, to-

gether with the following description thereof, will serve to moreclearly illustrate the features and 35 advantages of the presentinvention. Fig. 1 of the drawing is a sectional end elevation of afurnace embodying the features of the present invention, "and Fig. 2 isa sectional plan view of the same structure.

40 Referring to the drawing, the main furnace structure comprises sidewalls I and I, end walls 2 and 2', a roof 3 and a floor 4.

A centrally located vertical row 5 of tubes 6.

comprisestheheating coil or fluid conduit. The 45 tubes extendhorizontally between the end walls 2 and 2' of thefurnace and, in thecase here illustrated, are connected at their ends in series by means'of suitable return bends I. It will be understood that, although notillustratedin the drawing, parallel flow through the tubes of the fluidconduit may be employed, when desired, suitable headers (not shown),being provided in this case at opposite ends of the tubes. When 55series flow is employed through tubes 6 the general direction of flowthrough the tube bank may be either upward or downward, as desired.

Combustion zones 8 and 8' are provided on opposite sides of heating coil5 and suitable burners 9 supplied with fuel of any desired form 5 supplycombustion products to zones 8 and 8' through burner ports Ill and ill,respectively, located, in the case here illustrated, in roof 3 onopposite sides of the heating coil. A flue ll located above tube bank 5in the roof 3 of the 10 furnace permits the passage of combustionproducts to a suitable stack l2, controlled by damper 13. Preferably, asillustrated in the drawing, the burners and burner ports are inclinedslightly 15 toward the side walls l and I of the furnace so that theflame impinges against the side walls. The combustibles are dischargedfrom burners 9 with sufficient velocity to carry the flame downwardalong the sides I and I to near the floor 4 of the furnace where theflow of combustion gases is reversed, the gases passing then in anupward direction along opposite sides of the tubes 6 to flue II in theroof of the furnace. In this manner the tubes are. heated on oppositesides by direct radiation from the flames and by re-radiated heatfromthe walls of the furnace while convection heat from the hot combustiongases, as they pass upward around the tubes, is superimposed over theradiant heat. By firing opposite sides of the furnace equallysubstantially equal heating is obtained on opposite sides of thevertical center line through the tube bank so that each tube receivesheat at a substantially uniform rate on both sides. .By controlling theair-fuel ratio and the draft conditions the furnace may be fired in sucha manner that the decreasing amount of radiant heat from top to bottomof the tube bank is substantially compensated for by the increasingamount of convection heat, due to the counter-current flow of combustiongases over the tubes relative to the direction of the flame. Inthismanner substantially uniform heating conditions may be obtainedthroughout the entire length of the heatmg coil as well as on oppositesides thereof, thus permitting a higheraverage rate of heatingfor agiven maximum rate than is otherwise obtainable.

It will be understood that although the drawing and the foregoingdescription is confined to a down-fired, up-draft furnace, the featuresof the invention may be applied as well to a downdraft furnace firedfrom the bottom. This will be well understood by those familiar with thefurnace art without the necessity of additional drawings or description,the features involved in both cases being the same, namely, to impartradiant heat to opposite sides of a fluid conduit from flames and fromheated refractory surfaces and to impart additional convection heat tothe same fluid conduit by passing over the opposite sides thereofsimultaneously hot combustion gases in a direction counter-current tothe general I direction of the flame.

I claim as my invention:

1. In the heating of hydrocarbon oil to conversion temperatures, themethod which comprises passing the oil in a restricted stream seriallythrough a plurality of series connected, substantially horizontaltubular elements disposed in a common vertical plane approximatelymedially between a pair of spaced, parallel furnace walls, projectingflame of substantially uniform heat intensity downwardly along each ofsaid walls opposite said elements and in spaced relation with respect tothe latter, reversing the direction of flow of the combustion gasesresulting from the flames in the lower portion of the furnace below thelowermost of said elements, and

then passing the cumbustion gases upwardly sides of the tubes betweenthe tubes and the flames in a direction counter-current to the directionof movement of the flames along said walls.

3. A method for heating fluids which comprises passing the-fluid througha plurality of heating tubes disposed in a vertical plane between a pairof spaced vertical furnace walls, impinging flame angularly against eachof said walls on the side thereof facing the tubes and passing theflames and combustion gases in a vertical direction along said walls,then reversing the direction of flow of the combustion gases and passingthe same along both sides of the tubes between the tubes and the flamesin a direction countercurrent to the direction of movement of the flamesalong said walls.

4. A method for heating fluids which comprises passing the fluid througha plurality of heating tubes disposed in a vertical plane between a pairof spaced vertical furnace walls, impinging flame angularly against eachof said walls on the side thereof facing the tubes and passing theflames downwardly along said walls, and subsequently passing combustiongases resulting from the flames upwardly along both sides of the tubesbetween the latter and the flames.

5.- A method for heating fluids which comprises passing the fluidthrough a plurality of heating tubes disposed in a vertical planebetween a pair of spaced vertical furnace walls, iiiipinging flameangularly against each of said walls on the side thereof facing thetubes and passing the flames downwardly. along said walls, reversing thedirection of flow of the combustion gases resulting from the flames inthe lower portion of the furnace below the lowermost of said tubes, andthen passing the combustion gases upwardly along the opposite sides ofthe tubes between the latter and the flames.

6. A fluid heating apparatus comprising a furnace having a pair ofspaced vertical walls, a plurality of'heating tubes disposed in avertical 'plane between and spaced from said walls, means for projectingflame angularly against and vertically along each of said walls on theside thereof facing the tubes, and means for passing resultantcombustion gases along both sides of the tubes between the tubes and theflames in a direction countercurrent to the direction of movement of theflames along said walls. 7. A fluid heating apparatus comprising afurnace havinga pair of spaced vertical walls, a plurality of heatingtubes disposed in a vertical plane between and spacedfrom said walls,means for 'proje'ctin'g flame angularly against and downwardly alongeachof said walls on the side thereof facing the tubes, and means in thelower portion of the furnace below the lowermost of said tubes forreversing the direction of flow of the combustion gases resulting fromthe flames and for passing the gases upwardly along the opposite sidesof the tubes between the latter and the flames.

JOSEPH G. ALTHER.

